Background: Cognitive impairment in remitted late-life depression varies and might be associated with greater risk of dementia in some individuals. This study aimed to classify the subtypes of mild cognitive impairment (MCI) in late-life major depressive disorder in remission and to examine their clinical correlates and structural magnetic resonance imaging (MRI) features.
Methods: Elderly patients with major depressive disorder in remission and elderly comparisons were examined by a comprehensive battery of cognitive tasks. Proposed diagnostic criteria were used for MCI classification, and the degree of brain atrophy and white matter hyperintensity on MRI were evaluated.
Results: We found information-processing speed and memory were independent cognitive domains associated with late-life remitted major depressive disorder. Of the study cohort, 52.3% met the definition of MCI, including 28.5% with amnestic MCI (aMCI) and 23.8% with nonamnestic MCI (naMCI). A clinical correlate of aMCI was the late-onset of disorder (OR = 4.76; 95% CI = 1.57, 14.40) and of naMCI was a higher score on the Framingham stroke risk scale (OR = 1.39; 95% CI = 1.12, 1.72). The odds ratio of highest quartile of ventricular atrophy for aMCI compared to the comparisons was 3.65 (95% CI = 1.22, 10.96).
Conclusions: The central cognitive impairments among the elderly with major depressive disorder in remission were memory and information-processing speed, and over half of the subjects met the MCI diagnostic criteria. Different risk factors existed for the subtypes of aMCI and naMCI. Later-age onset of first episode and ventricular atrophy were associated with aMCI, whereas vascular risk factor were associated with naMCI. We suggest there were different pathogeneses between aMCI and naMCI in late-life major depressive disorder.